A small rack mounted UPS doesn't require a full-scale rebuild of infrastructure and would get you through almost all power fail scenarios. If you have 5 ZK servers, put 3 on one power source and give one of them the UPS. Then give put the other 2 on the second power source. If power source A fails, you keep 2+1 servers and if power source B fails, you keep 3.
If you can stand manual intervention during an emergency, you might be able to devise a recovery scenario. You can put 3 and 2 on A and B as above without a UPS. If B fails, you are fine. If A fails, you can go in and reconfigure the remaining nodes to only consider themselves as the quorum. This is not a good plan in general because ZK is reliable enough that people forget about it. That means it won't be top of mind in a disaster response. On Thu, Jul 15, 2010 at 10:30 AM, Sergei Babovich <sbabov...@demandware.com>wrote: > Three power sources obviously would solve the problem. Unfortunately at > this moment it does not seem to be feasible (we will need to rebuild the > whole existing infrastructure).